Mya and Deanna Cook at Fenway Park in Boston. (Courtesy of the Cook family)

After stern admonishments from the Massachusetts attorney general’s office, the Boston-area charter school that punished black girls for wearing braided hair extensions decided Sunday to suspend its controversial dress code policies that parents and activists say unfairly target children of color.

The Mystic Valley Regional Charter School first came under fire earlier this month for its hair — which ban hair extensions and hair more than two inches in height — after the parents of twin 15-year-olds Mya and Deanna Cook spoke to local media. They said their daughters had been kicked off school sports teams, banished from prom and received hours of detention for refusing to change their professionally braided hair.

Then last week, the American Civil Liberties Union filed a discrimination complaint with the state Education Department, and school officials met with state Attorney General Maura Healey. On Friday came the strongly worded letter, which said the attorney general’s office was investigating allegations that the school didn’t hold white students to the same standards.

Mystic Valley may be in violation of state and federal law, the letter said. It also instructed school officials to immediately stop enforcing the policy and withdraw any planned discipline for students, including the Cook twins.

The school had said previously that its strict dress code, which also bans makeup, nail polish and dyed hair, is meant to reduce wealth disparity among students. But the letter from Healey’s office, written by Civil Rights Division Chief Genevieve C. Nadeau, says that portions of the dress code “are not reasonably tailored to those goals, if they bear any relation at all.”

The school called for an emergency meeting of the public charter school’s board of trustees, which gathered Sunday. Officials were met by nearly 100 students, parents and community leaders who organized a rally with civil rights organizations before the meeting then stayed to watch, Aaron Cook, the father of the Cook twins, told The Washington Post.

But instead of publicly discussing the dress code issue, the board immediately went into a private executive session and “disappeared,” Cook said.

As the board of trustees moved into a private room for their executive meeting, the room full of attendees chanted “Let them learn!” and “Hey hey! Ho ho! This racist policy’s got to go!” Maya and Deanna Cook carried signs that said “Policy Disrespects Black Girls” and “We will not stop!!!” Another sign read, “Braids are beautiful.”

After waiting for two hours, Cook, his wife Colleen and their daughters left the meeting. About 30 minutes later, the board emerged and announced they would suspend the policies under investigation through the end of this school year, which commences in late June.

“The school will continue to work with the attorney general’s office to ensure that the uniform policy reflects our long-standing commitment to the rights of all of our students,” Alexander Dan, the school’s interim director, read from a prepared statement after the meeting, reported the Boston Globe. “Students who are either currently serving consequences, or accruing them, may immediately resume all before- and after-school activities.”

The Cooks took that to mean their daughters will not have to serve the 18 hours each of detention they had been assigned, though they plan to seek further clarification from the school. Deanna, a talented track runner, will be able to resume practicing with her teammates and compete at the state finals in two weeks, Aaron Cook said. And they hope Mya, who was told she couldn’t attend the prom, will get to dance now.

The Cooks are only cautiously optimistic, though.

“It’s a step in the right direction,” Aaron Cook said, “but there’s been so substantive change.”

His daughters, both sophomores and academically strong students, came to school in mid-April with braided hair extensions — essentially braids that combine artificial hair with their own hair — after telling their parents they no longer wanted to chemically straighten their hair.

They were learning more about black culture, they told their parents, who are white. The twins were adopted as toddlers, along with their three younger black siblings.

The dress code debate has sparked a broader conversation about diversity at the school, Cook said.

Frustrated students at the school previously told the Boston Globe that they had experienced a lack of racial sensitivity at the school, which is located about 10 miles north of Boston.

The student body is fairly diverse, which is part of the reason the Cooks chose it years ago. Of the 1,500 students there in grades K-12, 43 percent are people of color and within that, 17 percent are black, according to numbers from U.S. News and World Report.

But just one of the more than 150 teachers and staffers at Mystic Valley is black, reported the Boston Globe, and Cook said there are no African Americans on the school’s board of trustees.

He said the parents and students protesting the policy want a total overhaul, not just to the student handbook, but to the school leadership. More diversity, he said, is vital.

“They put on a Band-Aid on a symptoms through the end of the year. It’s certainly a positive step in the right direction, but it’s not over,” Cook told The Post. “I’m hopeful that they will permanently revise their policy so that they do not target girls of color.”

The Massachusetts Charter Public School Association, which criticized the school’s policies from the beginning, praised the board’s decision Sunday night.

“The Board took the right action to suspend its discriminatory policy, and now needs to rescind it permanently,” Marc Kenen, association executive director, said in a statement. “We are proud of the two young women, Deanna and Mya Cook, and their parents, for standing up for themselves and their rights.”